The present invention relates to testing a radio frequency (RF) data packet signal transceiver device under test (DUT), and in particular, enabling analysis of previously received and captured test data packets following detected changes in received signal characteristics while the DUT continues to transmit further data packets.
Many of today's electronic devices use wireless technologies for both connectivity and communications purposes. Because wireless devices transmit and receive electromagnetic energy, and because two or more wireless devices have the potential of interfering with the operations of one another by virtue of their signal frequencies and power spectral densities, these devices and their wireless technologies must adhere to various wireless technology standard specifications.
When designing such wireless devices, engineers take extra care to ensure that such devices will meet or exceed each of their included wireless technology prescribed standard-based specifications. Furthermore, when these devices are later being manufactured in quantity, they are tested to ensure that manufacturing defects will not cause improper operation, including their adherence to the included wireless technology standard-based specifications.
For testing these devices following their manufacture and assembly, current wireless device test systems employ a subsystem for analyzing signals received from each device. Such subsystems typically include at least a RF data packet signal transmitter, such as a vector signal generator (VSG), for providing the source signals to be transmitted to the device under test, and a RF data packet signal receiver, such as a vector signal analyzer (VSA), for receiving and analyzing signals produced by the DUT. The production of test signals by the VSG and signal analysis performed by the VSA are generally programmable so as to allow each to be used for testing a variety of devices for adherence to a variety of wireless technology standards with differing frequency ranges, bandwidths and signal modulation characteristics.
When testing such devices, triggering is often used to initiate action on a subsequent test event. For example, in advance of a test packet to be sent (e.g., by the DUT to the tester), a trigger would alert the tester to prepare for it. However, this necessarily requires that the tester know ahead in time when to capture one or more portions of a sequence of data packets being transmitted, as well as when to initiate testing (e.g., analysis) of the captured data packets. Further complicating this approach is the tendency for semiconductor integrated circuits (ICs) to intersperse non-deterministic self-calibration in the midst of a sequence of test data packets being sent. Capturing and analyzing such events (e.g., sequences of self-calibration data packets) provides little to no test data of value and is often cause for a test-error report.
Triggering often occurs in response to changes in one or more signal characteristics, following which action is taken on a following event. This means the device or system under test must know when the correct time is to respond and begin capturing packets. In many chipsets, some level of non-deterministic self-calibration is employed, which may be erroneously seen as an event to which the proper response is to begin capturing packets. Hence, it is necessary to detect these intervals of self-calibration and, once they have been completed, then begin processing (e.g., capturing or counting) packets.